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| Activation of the yeast Arp2/3 complex by Bee1p, a WASP-family protein |
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| Author(s): Winter D, Lechler T, Li R |
| Source: CURRENT BIOLOGY Volume: 9 Issue: 9 Pages: 501-504 Published: MAY 6 1999 |
| Times Cited: 149 References: 11 |
| Abstract: The Arp2/3 complex is a highly conserved cytoskeletal component that has been implicated in the nucleation of actin filament assembly [1]. Purified Arp2/3 complex has a low intrinsic actin nucleation activity, leading to the hypothesis that an unidentified cellular activator is required for the function of this complex [2,3]. We showed previously that mutations in the Arp2/3 complex and in Bee1p/Las17p, a member of the Wiskott-Aldrich syndrome protein (WASP) family, lead to a loss of cortical actin structures (patches) in yeast [4,5]. Bee1p has also been identified as an essential nucleation factor in the reconstitution of actin patches in vitro [6]. Recently, it was reported that WASP-like proteins might interact directly with the Arp2/3 complex through a conserved carboxy-terminal domain [7]. Here, we have shown that Bee1p and the Arp2/3 complex co-immunoprecipitate when expressed at endogenous levels, and that this interaction requires both the Arc15p and Arc19p subunits of the Arp2/3 complex. Furthermore, the carboxyterminal domain of Bee1p greatly stimulated the nucleation activity of purified Arp2/3 complex in vitro, suggesting a direct role for WASP family proteins in the activation of the Arp2/3 complex. Interestingly, deletion of the carboxy-terminal domain of Bee1p neither abolished the localization of the Arp2/3 complex, as had been suggested, nor resulted in a severe defect in cortical actin assembly. These results indicate that the function of Bee1p is not mediated entirely through its interaction with the Arp2/3 complex, and that factors redundant with Bee1p might exist to activate the nucleation activity of the Arp2/3 complex. |
| Document Type: Article |
| Language: English |
| Reprint Address: Li, R (reprint author), Harvard Univ, Sch Med, Dept Cell Biol, 240 Longwood Ave, Boston, MA 02115 USA |
Addresses:
1. Harvard Univ, Sch Med, Dept Cell Biol, Boston, MA 02115 USA |
| Publisher: CURRENT BIOLOGY LTD, 84 THEOBALDS RD, LONDON WC1X 8RR, ENGLAND |
| Subject Category: Biochemistry & Molecular Biology |
| IDS Number: 195DB |
| ISSN: 0960-9822 |
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